This application proposes the new theory of directed neuroendocrine- bacterial interactions as a mechanism governing the ability of an enteric pathogen to infect a host. This hypothesis is based on the in vitro and in vivo ability of the neuro-endocrine hormone norepinephrine (NE) to increase growth and production of virulence-associated factors of the enteric pathogen Escherichia coli O157:H7. High concentration of NE occur in foods such as ground beef which are contaminated by E. coli O157:H7. Equally high concentrations of NE also occur within the gastrointestinal tract due to enteric nervous system activity. The proposed research will therefore examine whether the presence of NE from the time of E. coli O157:H7 contamination of NE-rich foods to infection within the gut may be a factor mediating the development of hemorrhagic colitis. Results from this laboratory have shown that the effect of NE on E. coli O157:H7 contamination of NE-rich foods to infection within the gut may be a factor mediating the development of hemorrhagic colitis. Results from this laboratory have shown that the effect of NE on E. coli O157: H7 is due to the production of an autoinducer of growth. Thus, our Specific Aims are: 1) To determine the ability of a purified diet supplemented with levels of NE found in commonly contaminated foods to "prime" E. coli O157:H7 for the NE-rich environment within the gastrointestinal system; 2) To examine the ability of E. coli O157:H7 isolated from gastrointestinal trat of stressed and non-stressed mice since differences in luminal levels of NE between stressed and control animals would provide greater understanding of the recognized ability of stress to alter susceptibility to colitis; 4) To determine the ability of stress of alter the susceptibility of mice to oral challenge with E. coli O157:H7 exposed in vitro to control of NE supplemented diets; 5) To examine whether blockage of NE release within the gastrointestinal tract can alter susceptibility to challenge with E. coli P157:H7; and 6) To purify the serum-bound form of the NE-induced E. coli O157:H7 autoinducer of growth and determine its structure which may provide the basis for the development of agents to specifically interrupt bacterial division as well as identify the gene(s) involved in its production. Collectively, the above aims will seek to establish a direct cause and effect relationship between the NE content within food and the gastrointestinal trat to influence the ability of E. coli O157:H7 to cause infection. The demonstration of direct neuroendocrine-bacterial interaction as a mechanism in the pathogenesis of E. coli O157:H7 infection may yield new treatments for both the prevention and treatment of hemorrhagic colitis.